A novel eukaryotic expression vector pBlacZ was constructed, which was transfected into the cell lines of NIH/3T3, COS-1, CHO and the primary culture of murine dermatic fibroblasts in vitro, and also into the murine subcutaneous layer and skeletal muscles of rats in vivo. It was detected that the gene expression vector could encode the E. Coli beta-galactosidase effectively in all these histocytes. The results suggested that pBlacZ, as a novel expression vector, might have certain value of application.